It is known that hard floor surfaces such as stone, concrete, terrazzo, marble, granite etc. can be surfaced by dry grinding and/or polishing. Examples of machines that are suitable for such dry grinding are disclosed in WO03/076131 and U.S. Pat. No. 6,238,277B1. By dry grinding is meant grinding without supplying water or some other liquid to the floor surface and/or the tool finishing the floor surface. In rough grinding, it is not unusual that 40–120 kg of dust (dry weight) an hour are generated.
A drawback in dry grinding is that the working temperature, especially in connection with very hard floor surfaces, become so high that only a limited variety of tools can be used. For instance, when temperatures above 300° C. are measured on the surface of a tool, it can be assumed that the diamond tip of the tool is still hotter and thus risks being destroyed.
U.S. Pat. No. 5,605,493 discloses apparatus and methods for wet grinding of stone floors, such as marble and granite, where a lubricant is applied to the floor surface in grinding, to be sucked up by a wet vacuum cleaner after grinding. As stated in U.S. Pat. No. 5,605,493, efficient wet grinding requires an apparatus that can apply a lubricant, grind, and collect the lubricant.
It is known that wet grinding consumes 100–300 l of water/h, i.e. 2–6 l of water/m2.
A drawback in wet grinding is that a large and heavy amount of slurry, consisting of lubricant and grinding dust, must be handled and deposited. A further drawback in wet grinding is that extensive cleaning is required after each completed grinding operation.
There is thus a need for a method and an apparatus that eliminate the drawbacks of dry and wet grinding.